The Magento 188.8.131.52 release source code included the Magento Test Framework files. The Magento Test Framework (MTF) is a tool that can run automated functional tests, to assist in the development and implementation of Magento modules.
The test files are included in the Magento root /dev folder. The files are included for development purposes and might reveal your passwords or other sensitive information when accessed with malicious intent. The /dev directories and files are not protected by default and according to Magento, “these tests are not supposed to end up on production servers”.
Do not install these files in a production environment.
Delete the /dev/ folder from your production server.
Delete the /dev/ folder after upgrading to a newer version of Magento.